N-Methanesulfonic acid derivatives of 3-O-demethylistamycin B and production thereof

ABSTRACT

New semi-synthetic antibiotic derivative are formed from N-methanesulfonic acid derivatives of 3-O-demethylistamycin B which are less toxic than the parent 3-O-demethylistamycin B and retain usefully high antibacterial activity of the parent antibiotic. The new derivatives are produced by a method of N-sulfomethylation where 3-O-demethylistamycin B is reacted with an aldehyde such as paraformaldehyde and sulfurous acid or sulfite reagent.

SUMMARY OF THE INVENTION

This invention relates to a less toxic derivative of3-O-demethylistamycin B which is a new compound useful for therapeutictreatment of bacterial infections. More particularly, this inventionrelates to a new N-methane-sulfonic acid derivative of3-O-demethylistamycin B and also to a process for the production of saidderivative.

BACKGROUND OF THE INVENTION

Istamycin A or B is an aminoglycosidic antibiotic which was discoveredby the present inventors and is produced in the culture broth ofStreptomyces tenjimariensis (see Japanese patent applicationprepublication "Kokai" No. 145697/80; UK patent Application publn. GBNo. 2048855 A; and U.S. Pat. No. 4,296,106). 3-O-Demethylistamycin B isa new semi-synthetic aminoglycosidic antibiotic which was synthesized byus from istamycin B and exhibits a high antibacterial activity against awide range of gram-negative and gram-positive bacteria, includingPseudomonas aeruginosa (see Japanese patent application No. 125334/80;EPC patent application publication No. 048,549 A; and U.S. patentapplication Ser. No. 241,649). 3-O-Demethylistamycin B is represented bythe formula ##STR1##

It is known that a few of aminoglycosidic antibiotic substances areconverted into an N-methanesulfonic acid derivative thereof byN-sulfomethylation of some or all of the amino group(s) present in theantibiotic molecule, and that the N-methanesulfonic acid derivative soproduced exhibits a lower toxicity than the parent antibiotic. Anexample is N-methanesulfonic acid derivatives of kanamycin A (Journal ofAntibiotics, A 14, page 170 (1961)). Besides, it has been found by thepresent inventors that an N-methanesulfonic acid derivative of3',4'dideoxykanamycin B can be synthesized by interaction of 3',4'-dideoxykanamycin B, an aldehyde and sulfurous acid or an alkali metalhydrogen sulfite, and that this N-methanesulfonic acid derivative is oflower toxicity than the parent 3',4'-dideoxykanamycin B and hence isvaluable for therapeutic treatment of bacterial infections (see JapanesePatent Application "Kokai" No. 39653/77; UK Pat. No. 1507118; U.S. Pat.No. 4,091,202). It has also been found by us that an N-methanesulfonicacid derivative of istamycin A or B may be obtained as a new less toxicsubstance having useful antibacterial activity (see Japanese PatentApplication prepublication "Kokai" No. 39653/77; UK patent applicationpubln. GB No. 2083464 A; U.S. patent application Ser. No. 289,963).

Accordingly, if such a new antibiotic derivative of3-O-demethylistamycin B which shows a lower toxicity than the parent3-O-demethylistamycin B itself is provided, it will increase theapplications of 3-O-demethylistamycin B.

An object of this invention is to provide a new antibiotic derivative of3-O-demethylistamycin B which retains useful antibacterial activity of3-O-demethylistamycin B but exhibits a lower toxicity than that of3-O-demethylistamycin B. The outer object is to provide a process forthe preparation of such new antibiotic derivative of3-O-demethylistamycin B. Another objects of this invention will be clearfrom the following descriptions.

As a result of our research, we have now found that as new compounds,N-methanesulfonic acid derivatives of 3-O-demethylistamycin B can besynthesized by reaction of 3-O-demethylistamycin B of the above formula(I) or an acid addition salt thereof with an aldehyde of the formula:

    RCHO                                                       (IV)

wherein R is as defined later and also with sulfurous acid or an alkalior alkaline earth metal hydrogen sulfite (including ammonium hydrogensulfite) of the formula:

    MHSO.sub.3                                                 (V)

wherein M is a hydrogen atom, an alkali metal, alkaline earth metal atomor ammonium cation. We have confirmed that these N-methanesulfonic acidderivatives of 3-0-demethylistamycin B are remarkedly lower toxicitythan 3-O-demethylistamycin B. 3-O-Demethylestamycin B contains threeamino groups and one methylamino group per molecule as will be clearfrom the above formula (I), and it has been found that the newN-methanesulfonic acid derivative of 3-O-demethylistamycin B prepared issuch one in which one, two, three or four groups of the aforesaid threeamino groups and one methylamino group present in the molecule has orhave been N-sulfomethylated, that is to say, substituted with amethanesulfonate group of the formula:

    --CHRSP.sub.3 M                                            (II)

wherein R is a hydrogen atom, an alkyl group, preferably an alkyl groupof 1˜4 carbon atoms, a substituted alkyl group, a phenyl group or asubstituted phenyl group, and M represents a hydrogen atom, an ammoniumcation, an alkali metal or an alkaline earth metal atom. The totalnumber of the N-sulfomethylated amino and methylamino groups present inthe resulting N-methanesulfonic acid derivative of 3-O-demethylistamycinB amounts to 1, 2, 3, or 4, depending upon the molar proportions of thealdehyde and the sulfurous acid or sulfite compound employed for 1 molarproportion of 3-O-demethylistamycin B.

DETAILED DESCRIPTION OF THE INVENTION

According to a first aspect of this invention, there is provided as anew compound, an N-methanesulfonic acid derivative of3-O-demethylistamycin B of the formula: ##STR2## wherein one, two, threeor four of the R' groups denote(s) each a group --CHRSO₃ M and theremaining other R' group(s) denote(s) each a hydrogen atom, where R is ahydrogen atom, an alkyl group, a substituted alkyl group, a phenyl groupor a substituted phenyl group, and M is a hydrogen atom, an ammoniumcation, an alkali metal atom or an alkaline earth metal atom.

When R in the group -CHRSO₃ M shown above denotes an alkyl group, it maypreferably be a lower alkyl containing 1 to 4 carbon atoms, such asmethyl, ethyl, n-butyl and n-propyl. R may also be a substituted alkylgroup such as a lower alkyl bearing one or more methoxy or chlorosubstituents thereon. Suitable examples of the substituted alkyl groupinclude methoxymethyl, monochloromethyl and dichloromethyl. When R is asubstituted phenyl group, it may be, for example, p-methoxyphenyl ando-hydroxyphenyl. According to a particular embodiment of the firstaspect invention, there is provided an N-methanesulfonic acid derivativeof 3-O-demethylistamycin B which is selected from (1)3-O-demethylistamycin B-mono-N-nethanesulfonic acid sodium salt, namelythe compound of the formula (III) where one R' group is a group--CHRSO₃, the remaining three R' groups are each a hydrogen atom, R is ahydrogen atom and M is sodium; (2) 3-O-demethylistamycinB-di-N-methanesulfonic acid sodium salt, namely the compound of theformual (III) where two R' groups are each a group --CHRSO₃, theremaining two R' groups are each a hydrogen atom, R is a hydrogen atomand M is sodium; (3) 3-O-demethylistamycin B-tri-N-methanesulfonic acidsodium salt, namely the compound of the formula (III) where three R'groups are each a group --CHRSO₃, the remaining one R' group is ahydrogen atom, R is a hydrogen atom and M is sodium; and (4)3-O-demethylistamycin B-tetra-N-methanesulfonic acid sodium salt, namelythe compound of the formula (III) where all four R' groups are each agroup --CHRSO₃, R is a hydrogen atom and M is sodium.

Particular examples of the N-methanesulfonic acid derivative of3-O-demethylistamycin B obtained according to this invention are listedbelow together with physicochemical properties of them:

(1) 3-O-Demethylistamycin B-mono-N-methanesulfonic acid sodium salt ofthe formula C₁₆ H₃₂ N₅ O₅ (CH₂ SO₃ Na). This compound is in the form ofa colorless powder which has no definite melting point, decomposesgradually at 210° C. and shows a specific optical rotation [α]_(D) ²³+72° (c 1, water).

Elemental analysis: Found: S 7.41%. Calcd.: S 6.52%.

(2) 3-O-Demethylistamycin B-di-N-methanesulfonic acid sodium salt of theformula C₁₆ H₃₁ N₅ O₅ (CH₂ SO₃ Na)₂. This compound is in the form of acolorless powder which has no definite melting point, decomposesgradually at 220° C. and shows a specific optical rotation [α]_(D) ²³+63° (c 1, water).

Elemental analysis: Found: S 11.17%. Calcd.; S 10.55%.

(3) 3-O-Demethylistamycin B-tri-N-methanesulfonic acid sodium salt ofthe formula C₁₆ H₃₀ N₅ O₅ (CH₂ SO₃ Na)₃. This compound is in the form ofa colorless powder which has no difinite melting point, decomposesgradually at 230° C. and shows a specific optical rotation [α]_(D) ²³+57° (c 1, water).

Elemental analysis: Found: S 13.14%. Calcd.: S 12.73%.

(4) 3-O-Demethylistamycin B-tetra-N-methanesulfonic acid sodium salt ofthe formula C₁₆ H₂₉ N₅ O₅ (CH₂ SO₂ Na)₄. This compound is also in theform of a colorless powder which has no definite melting point,decomposes gradually at 230° C. and shows a specific optical rotation[α]_(D) ²³ +50° (c 1, water).

Elemental analysis: Found: S 14.60%. Calcd.: S 15.65%

Each of the above-mentioned particular 3-O-demethylistamycin BN-methanesulfonic acid derivatives is readily soluble in water butlittle soluble or insoluble in a lower alkanol such as methanol, ethanoland 1-butanol, tetrahydrofuran, dioxane and N,N-dimethylformamide.

The new compounds of this invention exhibit high antibacterial activityagainst a variety of gram-negative and gram-positive bacteria, includingPseudomonas aeruginosa, was will be clear from antibacterial spectra ofthem shown in Table 1 below, wherein there are set out the minimuminhibitory concentrations (mcg/ml) of 3-O-demethylistamycinB-mono-N-methanesulfonic acid sodium salt [abbreviated as Compound (1)];3-O-demethylistamycin B-di-N-methanesulfonic acid sodium salt[abbreviated as Compound (2)]; 3-O-demethylistamycinB-tri-N-methanesulfonic acid sodium salt [abbreviated as Compound (3)];and 3-O-demethylistamycin B-tetra-N-methanesulfonic acid sodium salt[abbreviated as Compound (4)] of this invention against various bacteriawhich have been estimated according to a standard serial dilution methodusing Mueller-Hinton agar as the incubation medium, the incubation beingmade at 37° C. for 17 hours. Minimum inhibitory concentrations (mcg/ml)of the parent 3-O-demethylistamycin B were also estimated in the samemanner for the comparison purpose and also are shown in Table 1.

                                      TABLE 1                                     __________________________________________________________________________                    Minimum Inhibitory concentrations (mcg/ml)                                                            3-O--demethyl-                                        Compound                                                                            Compound                                                                            Compound                                                                            Compound                                                                            istamycin B                           Test Microorganism                                                                            (1)   (2)   (3)   (4)   (comparative)                         __________________________________________________________________________    Staphylococcus aureus 209P                                                                    0.78  1.56  0.78  1.56  0.39                                  Staphylococcus aureus Ap01                                                                    1.56  1.56  1.56  3.13  0.39                                  Escherichia coli K-12                                                                         1.56  1.56  1.56  3.13  0.78                                  Escherichia coli K-12 R5                                                                      6.25  12.5  12.5  25    3.13                                  Escherichia coli K-12 ML1629                                                                  1.56  3.13  3.13  6.25  1.56                                  Escherichia coli K-12 LA290 R55                                                               3.13  3.13  6.25  12.5  0.78                                  Escherichia coli JR66/W677                                                                    6.25  6.25  6.25  25    1.56                                  Escherichia coli K-12 C600 R135                                                               3.13  3.13  3.13  6.25  1.56                                  Escherichia coli JR225                                                                        1.56  1.56  1.56  3.13  0.78                                  Serratia marcescens                                                                           6.25  12.5  12.5  25    1.56                                  Providencia Pv 16                                                                             3.13  3.13  3.13  6.25  0.78                                  Pseudomonas aeruginosa A3                                                                     0.78  3.13  0.78  1.56  0.20                                  Pseudomonas aeruginosa H9                                                                     12.5  12.5  12.5  25    12.5                                  Pseudomonas aeruginosa TI-13                                                                  6.25  6.25  6.25  25    6.25                                  Pseudomonas aeruginosa GN315                                                                  12.5  6.25  12.5  25    6.25                                  __________________________________________________________________________

The N-methanesulfonic acid derivatives of 3-O-demethylistamycin Baccording to this invention have a remarkedly reduced acute toxicity, ascompared to the parent 3-O-demethylistamycin B, notwithstanding that theformer compounds retain high antibacterial activity against variousbacteria.

Acute toxicity of the various N-methanesulfonic acid derivatives of3-O-demethylistamycin B of the invention has been determined by thefollowing procedure:

A test compound was diissolved in 0.25 ml of a physiological salinesolution and the solution of the test compound so prepared wasintravenously administered into a series of mouse groups each consistingof six mice (ICR strain, adult female, body weight 20 g±0.5 g) as thetest animal, so that the test compound was given to each mouse at adosage of 1000 mg/kg. Acute toxicity of 3-O-demethylistamycin B was alsoestimated in the same manner as above for the comparison purpose. It wasthen observed that all mice survived for more than 14 days when theN-methanesulfonic acid derivatives of 3-O-demethylistamycin B wereadministered at a dosage of 1000 mg/kg (LD₅₀ > 1000 mg/kg), whereas allmice died within 24 hours when 3-O-demethylistamycin B (comparative) wasadministered at a dosage of 320 mg/kg (LD₅₀ 160˜320 mg/kg).

From the test results of Table 1 and of acute toxicity as mentionedabove, it is evident that the new compounds of the invention haveremarkedly reduced toxicity but retain usefully high antibacterialactivity against various bacteria.

The new compounds of the inventionm are effective in the treatment ofbacterial infections when administered intramuscularly in the dosagerange of about 100 mg to about 1000 mg per day in divided doses three orfour times a day. Generally, the new compounds may be administeredorally, intraperitoneally, intravenously or intramuscularly using anypharmaceutical form known to the art for such administration and in asimilar manner to kanamycins. Examples of pharmaceutical forms of oraladministration are powders, capsules, tablets, syrup and the like.

The new N-methanesulfonic acid derivatives of 3-O-demethylistamycin B ofthe above formula (III) according to the invention may be prepared byreaction of 3-O-demethylistamycin B, either in the form of the free baseor an acid addition salt thereof, with an aldehyde of the formula:

    RCHO                                                       (IV)

wherein R is a hydrogen atom, an alkyl group, particularly a lower alkylgroup of 1˜4 carbon atoms, a substituted alkyl group, a phenyl group ora substituted phenyl group, and sulfurous acid or a sulfite of theformula:

    MHSO.sub.3                                                 (V)

wherein M is a hydrogen atom, an ammonium cation, an alkali metal atomor an alkaline earth metal atom. The resulting N-methanesulfonic acidderivatives contains a number of the N-methanesulfonate group(s) whichtakes a varying value of 1, 2, 3 or 4 depending upon the molarproportions of the aldehyde and the sulfurous acid or sulfite compoundemployed for 1 molar proporation of 3-O-demethylistamycin B. Thealdehyde and the sulfurous acid or sulfite may be reacted simultaneouslywith 3-O-demethylistamycin B, or alternatively either one of thealdehyde reagent and the sulfurous acid or sulfite reagent may bereacted at first with 3-O-demethylistamycin B before the resultingreaction product is reacted with the other reagent.

According to a second aspect of the present invention, therefore, thereis provided a process for the preparation of an N-methanesulfonic acidderivative of 3-O-demethylistamycin B of the formula ##STR3## whereinone, two, three or four of the R' groups denote(s) each a group --CHRSO₃M and the remaining other R' group(s) denote(s) each a hydrogen atom,where R is a hydrogen atom, an alkyl group, a substituted alkyl group, aphenyl group or a substituted phenyl group, and M is a hydrogen atom, anammonium cation, an alkali metal atom or an alkaline earth metal atom,which comprises reacting 3-O-demethylistamycinB or an acid addition saltthereof with an aldehyde of the formula

    RCHO                                                       (IV)

wherein R is as defined above, and sulfurous acid or a sulfite of theformula

    MHSO.sub.3                                                 (V)

wherein M is as defined above.

When sulfurous acid of the above formula (V) where M is a hydrogen atomis used as one of the reagents in the process of the invention, it mayconveniently be used in the form of gaseous sulfur dioxide. However, itis feasible, of course, to employ aqueous sulfurous acid. In stead ofthe sulfurous acid reagent, an alkali metal, alkaline earth metal orammonium hydrogen sulfite may be used as an equivalent agent. Sodiumhydrogen sulfite, potassium hydrogen sulfite, lithium hydrogen sulfiteand ammonium hydrogen sulfite are suitable as the sulfite for thepurpose of the invention. Suitable examples of the aldehyde reagent ofthe formula (IV) available for the invention include paraformaldehyde,acetaldehyde, methoxyacetaldehyde, monochloroacetaldehyde,dichloroacetaldehyde, glyoxal, propionaldehyde, n-butylaldehyde,benzaldehyde, p-methoxybenzaldehyde and salicylaldehyde.

In preparing the new compound of the above formula (III) according tothe invention, either one of the aldehyde reagent of the formula (IV)and the sulfurous acid or sulfite reagent of the formula (V) may bereacted at first with 3-O-demethylistamycin B. Thus, it is feasible tocarry out the process in such a manner that the aldehyde reagent isreacted at first with 3-O-demethylistamycin B to produce thecorresponding Schiff's base so formed, this Schiff's base is isolatedand then reacted with the sulfurous acid or sulfite reagent to yeild thedesired 3-O-demethylistamycin B N-methanesulfonic acid derivative (III)as the final product. Alternatively, it is possible to conduct theprocess in such a manner that the sulfurous acid or sulfite reagent isat first reacted with 3-O-demethylistamycin B to convert the latter intothe form of an acid-addition salt with sulfurous acid, which issubsequently reacted with the aldehyde reagent to yield the desiredN-methanesulfonic acid derivative (III) as the final product. Moreover,an adduct of both the reagents (IV) and (V) such as sodiumhydroxymethanesulfonate or glyoxal sodium hydrogen sulfite may also beused in the process of the invention. Namely, this adduct may bedirectly reacted with 3-O-demethylistamycin B to yield the desiredN-methanesulfonic acid derivative (III) as the final product.

As will be clear from the above, the molar proportions of the aldehydereagent and the sulfurous acid or sulfite reagent to be interacted with3-O-demethylistamycin B may vary from 1 molar to 4 molar proportions for1 molar proportion of 3-O-demethylistamycin B. The N-methanesulfonicacid derivatives obtained as the final product by the process of theinvention contain the methanesulfonate component at different contentsdepending on the molar proportions of the aldehyde reagent and thesulfurous acid or sulfite reagent employed, but they usually containone, two, three of four N-methanesulfonate groups per molecule of3-O-demethylistamycin B.

Generally, the process may be carried out preferably in water as thereaction medium, but a small proportion of a lower alcohol such asmethanol and ethanol may be added to the reaction medium when thestarting aldehyde (IV) is hardly soluble in water. The process mayreadily be conducted at a temperature of 0° to 70° C. for a reactionperiod of usually 0.5 to 24 hours.

For recovery of the final product from the reaction solution, it may beprecipitated as a colorless deposit by adding thereto a volume of suchan organic solvent in which the desired product is sparingly soluble,such as a lower alcohol e.g. methanol and ethanol, tetrahydrofuran,dioxane and N,N-dimethylformamide. The colorless precipitate formed infiltered out, washed with methanol or ethanol and then dried to affordthe desired 3-O-demethylistamycin B N-methanesulfonic acid derivative(III) in a yield of 55% or more.

That the new derivatives of 3-O-demethylistamycin B as produced by theprocess of the invention have the molecular structure corresponding tothat of an N-methanesulfonic acid derivative has been confirmed from theinfra-red absorption spectrophotometry as well as from the experimentsshowing that they liberate formaldehyde when hydrolyzed with dilutedhydrochloric acid.

As stated before, the new compounds of the invention are effective intreatment of bacterial infections. According to a third aspect of theinvention, therefore, there is provided an antibacterial pharmaceuticalcomposition comprising an antibacterially effective amount of a3-O-demethylistamycin B N-methanesulfonic acid derivative of the formula(III), in combination with a pharmaceutically acceptable carriertherefor.

The invention is now illustrated with reference to the followingExamples which are in no way limitative for the invention.

EXAMPLE 1

3-O-Demethylistamycin B (free base) (37.5 mg; 0.1 millimoles) wasdissolved in water (0.11 ml), and the resultant aqueous solution wasadmixed with sodium hydrogen sulfite (10.4 mg; 0.1 millimoles) andparaformaldehyde (3 mg; 0.1 millimoles). The admixture obtained wasshaken at ambient temperature overnight for the reaction. Ethanol (2.5ml) was added to the reaction solution to deposit a colorlessprecipitate. This precipitate was collected by filtration and driedunder reduced pressure to a constant weight, affording 28.0 mg of acolorless powder of 3-O-demethylistamycin B-mono-N-methanesulfonic acidsodium salt which decomposed gradually at 210° C. [α]_(D) ²³ +72° (c 1,water).

EXAMPLE 2

3-O-Demethylistamycin B (free base) (37.5 mg; 0.1 millimoles) wasdissolved in water (0.11 ml), and the resultant aqueous solution wasadmixed with sodium hydrogen sulfite (20.9 mg; 0.2 millimoles) andparaformaldehyde (6 mg; 0.2 millimoles). The admixture obtained wasshaken at ambient temperature overnight for the reaction. Ethanol (2.5ml) was added to the reaction solution to deposit a colorlessprecipitate. This precipitate was collected by filtration and driedunder reduced pressure to a constant weight, affording 55.7 mg of acolorless powder of 3-O-demethylistamycin B-di-N-methanesulfonic acidsodium salt which decomposed gradually at 220° C. [α]_(D) ²³ +63° (c 1,water).

EXAMPLE 3

3-O-Demethylistamycin B (free base)(37.5 mg; 0.1 millimoles) wasdissolved in water (0.11 ml), and the resultant aqueous solution wasadmixed with sodium hydrogen sulfite (31.2 mg; 0.3 millimoles) andparaformaldehyde (9 mg; 0.3 millimoles). The admixture obtained wasshaken at ambient temperature overnight for the reaction. Ethanol (2.5ml) was added to the reaction solution to deposit a colorlessprecipitate. This precipitate was collected by filtration and driedunder reduced pressure to a constant weight, affording 71.2 mg of acolorless powder of 3-O-demethylistamycin B-tri-N-methanesulfonic acidsodium salt which decomposed gradually at 230° C. [α]_(D) ²³ +57° (c 1,water).

EXAMPLE 4

3-O-Demethylistamycin B (free base)(37.5 mg; 0.1 millimoles) wasdissolved in water (0.11 ml), and the resultant aqueous solution wasadmixed with sodium hydrogen sulfite (41.7 mg; 0.4 millimoles) andparaformladehyde (12.1 mg; 0.4 millimoles). The admixture obtained wasshaken at ambient temperature overnight for the reaction. Ethanol (5 ml)was added to the reaction solution to deposit a colorless precipitate.This precipitate was collected by filtration and dried u nder reducedpressure to a constant weight, affording 87 mg of a colorless powder of3-O-demethylistamycin B-tetra-N-methanesulfonic acid sodium salt whichdecomposed gradually at 230° C. [α]_(D) ²³ +50° (c 1, water).

We claim:
 1. An N-methanesulfonic acid derivative of3-O-demethylistamycin B represented by the formula ##STR4## wherein one,two, three or four of the R' groups denote(s) each a group --CHRSO₃ Mand the remaining other R' group(s) denote(s) each a hydrogen atom,where R is a hydrogen atom, an alkyl group, a phenyl group, and M is ahydrogen atom, an ammonium cation, an alkali metal atom or an alkalineearth metal atom.
 2. A compound according to claim 1 which is3-O-demethylistamycin B-mono-N-methanesulfonic acid sodium salt, thecompound of the formula (III) where one R' group is a group --CHRSO₃ Mand the remaining three R' groups are each a hydrogen atom; and R is ahydrogen atom and M is sodium.
 3. A compound according to claim 1 whichis 3-O-demethylistamycin B-di-N-methanesulfonic acid sodium salt, thecompound of the formula (III) where two R' groups are each a group--CHRSO₃ M and the remaining two R' groups are each a hydrogen atom; andR is a hydrogen atom and M is sodium.
 4. A compound according to claim 1which is 3-O-demethylistamycin B-tri-N-methanesulfonic acid sodium salt,the compound of the formula (III) where three R' groups are each a group--CHRSO₃ M and the remaining one R' group is a hydrogen atom; and R is ahydrogen atom and M is sodium.
 5. A compound according to claim 1 whichis 3-O-demethylistamycin B-tetra-N-methanesulfonic acid sodium salt, thecompound of the formula (III) where all four R' groups are each a group--CHRSO₃ M and R is a hydrogen atom and M is sodium.
 6. An antibacterialpharmaceutical composition comprising an antibacterially effectiveamount of a compound according to claim 1, in combination with apharmaceutically acceptable carrier therefor.